Version 1.6.0

API

• Various performance optimizations
  • 1 and 2 element Attributes instances now bypass some logic to reduce object allocations.
  • The result of hashCode() of AttributeKey is now cached.
  • Checks for base-16 validity of TraceId and SpanId have been optimized.
  • Internally created SpanContext instances now bypass unneeded validation.

Semantic Conventions (alpha)

• The SemanticAttributes and ResourceAttributes classes have been updated to match the semantic
  conventions as of specification release 1.6.1.

SDK

• The io.opentelemetry.sdk.trace.ReadableSpan interface has been expanded to include
  a getAttribute(AttributeKey) method.
• The io.opentelemetry.sdk.trace.SpanLimits class now supports enforcing a maximum Span attribute
  length (measured in characters) on String and String-array values.

Exporters

• The OTLP exporters have been undergone a significant internal rework. Various performance
  optimizations have been done on process of converting to the OTLP formats. Because of this, the exporter libraries
  no longer have a runtime dependency on the opentelemetry-proto artifact, or transitively protobuf. If you were
  using code from these libraries through these transitive dependencies, you will need to add them directly to your
  build.
• The OTLP metric exporter no longer exports the deprecated metric Labels, only Attributes. This
  means that your collector MUST support at least OTLP version 0.9.0 to properly ingest metric
  data.
• BREAKING CHANGE: The OtlpHttpMetricExporter class has been moved into
  the io.opentelemetry.exporter.otlp.http.metrics package.
• BUGFIX: The OtlpGrpcSpanExporter and OtlpGrpcMetricExporter will now wait for the underlying
  grpc channel to be terminated when shutting down.
• The OTLP exporters now optionally support gzip compression. It is not enabled by default.

SDK Extensions

• The AwsXrayIdGenerator in the opentelemetry-sdk-extension-aws module has been deprecated. This
  implementation has been superseded by the one in
  the opentelemetry-java-contrib
  project and will not be maintained here going forward.

Auto-configuration (alpha)

• The otel.traces.exporter/OTEL_TRACES_EXPORTER option now supports a comma-separated list of
  exporters.
• The Metrics SDK will no longer be configured by default. You must explicitly request an exporter
  configuration in order to have a Metrics SDK configured.
• BREAKING CHANGE: All SPI interfaces are now in a separate module from the autoconfiguration
  module: opentelemetry-sdk-extension-autoconfigure-spi.
• BREAKING CHANGE: ConfigProperties and ConfigurationException have been moved to a new
  package (io.opentelemetry.sdk.autoconfigure.spi) and
  module (opentelemetry-sdk-extension-autoconfigure-spi).
• BREAKING CHANGE: All SPI interfaces now take a ConfigProperties instance on their methods.
• BUGFIX: Exceptions thrown during the loading of an SPI implementation class are now handled more
  gracefully and will not bubble up unless you have explicitly requested the bad implementation as
  the one to use.
• You can now specify gzip compress for the OTLP exporters via the otel.exporter.otlp.compression
  /OTEL_EXPORTER_OTLP_COMPRESSION configuration option.
• You can now specify maximum Span attribute length via the otel.span.attribute.value.length.limit
  /OTEL_SPAN_ATTRIBUTE_VALUE_LENGTH_LIMIT configuration option.

Metrics (alpha)

• BREAKING CHANGES: The metrics SDK has numerous breaking changes, both behavioral and in the SDK's
  configuration APIs.
  • The default aggregation for a Histogram instrument has been changed to be a Histogram, rather than a Summary.
  • Registration of Views has undergone significant rework to match the current state of the SDK specification. Please reach out on CNCF slack in the #otel-java channel, or in a github discussion if you need assistance with converting to the new Views API.
  • The OTLP exporter no longer exports the deprecated metric Labels, only Attributes. This means that your collector MUST support at least OTLP version 0.9.0 to properly ingest metric data.
  • It is no longer possible to provide custom aggregations via a View. This feature will return in the future.